Dysfunction of the endothelial-platelet pathway in patients with erectile dysfunction before and after daily treatment with tadalafil.

Platelet activation results from the exposure of receptors on the surface of the platelet to specific structures on the vessel wall. The aim of this study was to assess the serum concentrations of apoptotic endothelial microparticles (EMPa) and the vitronectin receptor (VR) in patients with erectile dysfunction (ED) before and after treatment with tadalafil. This study included 50 patients with arterial ED. EMPa and VR levels were measured by using flow cytometry. The CD45(neg)-CD144(pos)-annexin V(Pos) events were defined as EMPa, and the CD51(pos)-CD61(pos) events were defined as VR. Patients with ED were evaluated before and after daily treatment with 5 mg tadalafil for 90 days. Patients with arterial ED had serum concentrations of EMPa and VR significantly higher than the control group at baseline. After tadalafil, the serum concentrations of EMPa and VR of the patients with arterial ED were significantly lower than before treatment, but significantly higher than controls. Patients with arterial ED expressed higher levels of both EMPa that are associated with dysfunction of the arterial endothelial pathway and VR-expressing platelet-endothelial elements. Chronic treatment with tadalafil reduced endothelial apoptosis in these patients and also reduced VR expression.